In the bowl of a stand mixer, whisk together all-purpose four, semolina, and salt. Attach dough hook to stand mixer. On low speed, slowly add whisked eggs a little bit at a time. Once all eggs have been incorporated, increase speed to medium and knead until dough is a smooth, cohesive mass. Knead/mix for about 5-6 minutes. If dough is too tough or dry, add 1/2 Tbsp of water at a time until smooth. (I used 1 1/2 Tbsp)
Keep dough in mixing bowl and cover with plastic wrap. Let sit and rest at room temperature for one hour.
Transfer dough to lightly floured surface and divide dough into 8 equal parts. Working with one piece at a time, flatten dough into a rectangle. Lightly dust the dough and the pasta roller mixer attachment (or pasta machine).
With the roller on the widest setting, pass the pasta through the machine's rollers a couple times. Begin to adjust the pasta machine setting to be thinner, passing the dough through once or twice at each setting. Keep the machine running at low-medium or medium speed.
*If rolling the pasta by hand: flatten dough into rectangle with your hands. Place dough on lightly floured work surface, begin rolling dough with a floured rolling-pin. Be sure to constantly move the dough by lifting it to make sure it is not sticking to the surface. Continue to roll and thin out dough to your desired thickness.
Once the pasta is at your desired thickness ( I took mine down to the 5th setting), cut into your desired shapes. I cut 1/4'' inch wide strips to make the fettuccine. You can cut by hand or use a pasta attachment cutter. Once you have cut the pasta, drape over a clean large sauce pot or the back of a chair to dry the pasta for 5-10 minutes before cooking.
To cook the pasta, fill a large sauce pot with salted water. I've been told to salt the water until it tastes like sea water, but the amount of salt is up to you. Cover the pot and wait for the water to boil.
Gently drop in pasta into the boiling water. Stir the pasta only once or twice. Do not over the pot. Let the pasta come back to a rolling boil. Cook for 2-4 minutes until pasta is al dente, or firm to the bite.
Before you drain the pasta, reserve 1 cup of pasta water. Drain pasta. Transfer pasta to clean large bowl. Dress with sauce right away.